BRAKE EFFICIENCY.

Hawera Star, Volume XLVIII, 23 February 1929, Page 12

BRAKE EFFICIENCY.

STEADY IMPROVEMENT

Each year the average speed of traffic increases as does the average speed of the car, and also the volume of ears on the congested road. Brakes must improve equally as rapidly, as the speed of the car; more rapidly, in fact, for brakes have been a long way behind speed for years past and it is only since the relatively recent arrival of fourwheel brakes that general safety has been at all assured. Progress lias been made with brake systems, and, indeed is being made quite rapidly by those manufacturers of cars who are keen enough to study the performance of efficient contemporaries. year or two ago, cars with four-wheel brakes took 9Oft to 110 ft to pull up in emergency from 40. m.p.h.-. To-day the brake system urgently needs attention if the vehicle cannot make any. emergency stop from that speed in 60ft or 70ft and stop smoothly at that.

Attention to efficiency in the mechanism lias obtained these results. Men and women are capable of exerting a certain- average pressure with a single foot, and there Is a limit of only a few inches of travel over which tills pressure can comfortably bo maintained. Those two factors provide all the leverage for brake application that is available. If the system of leverages and tie-rods leading to the brake shoes is efficiently designed and made, then this available force is quite sufficient to give adequate control for a car up to 20 h.p. and capable, of 60 m.p.h. I Larger cars of greater weight and speed ! need some form of mechanical assist- j ance, or servo system, in order to re-

lievo the driver of hard work. Servo motor brakes of the vacuum operating type, such as the Dewandre and the Westinghouse, are ceasing to find place on the small and medium-sized car because detail improvement in actuating gear is making them less neee-ssairy, and partly because of price, but on larger cars, in which expense is more or less a secondary'consideration, such systems are falling into, regular use, to say nothing of the mechanical type of servo brake and the hydraulically assisted brake. s